The present invention relates to a cutterhead with a body on which knife holders are mounted and to which chopper knives are fastened.
Cutterheads are used in installations of various designs for the chopping of materials from the agricultural, forest products and municipal economies and from other areas of the economy, for example, from plastics and food products. Such cutter heads are equipped with several knives usually arranged symmetrically, whose cutting edges may either be parallel to, or inclined to, the axis of rotation of the cutterhead and thereby produce a chopping or a drawing cut. The knives are fastened to knife holders, as a rule so that they can be removed, for example, for replacement after reaching a wear limit. The knife holders are attached to the cutterhead body either in a permanent or removable fashion, and the cutterhead body is of a known design, for example, where it consists of a cylindrical drum shell, or of an open design with disks and ring-shaped fastener retainers, or as a combination of closed and open design which results in a semi-closed configuration.
U.S. Pat. No. 5,878,970, granted Mar. 9, 1999, discloses a cutterhead that is provided with knives fastened to knife holders. It is recommended that the leading surface of the knife holder, as seen in the direction of rotation, be provided with a separate angled or rounded impeller blade part, in order to reduce wear and to prevent chopped material from adhering to this surface. A rounded form of the impeller blade part with a smooth surface, free from edges or projections, has aerodynamic advantages.
The problem underlying the invention is seen as that of making available a cost effective and easily mounted cutterhead knife holder that makes possible a smooth conveying of the chopped crop.
According to the present invention there is provided a cutterhead, for example for chopping agricultural crop material, having an improved impeller blade surface associated with each knife and its holder.
A broad object of the invention is to provide a cutterhead including a plurality of knife holders which each define at least a radially outer portion of a smooth curved surface extending from an underside location of the knife adjacent its cutting edge to a mounting surface for the knife holder.
A more specific object of the invention is to provide a cutterhead, as set forth in the previous object, wherein, in accordance with a first embodiment, an impeller blade surface is defined in its entirety by a leading surface of each knife holder and a radially inner surface portion of the associated knife, with the leading surface of the holder defining a smooth curved, one-piece impeller surface that extends radially outward from a mounting surface of the knife holder and blends smoothly into the radially inner surface portion of the knife.
Yet another specific object of the invention is to provide a cutterhead, as defined in the previous objects, wherein each knife holder, according to a second embodiment, includes a central removable rail forming part of the leading surface of the holder which blends smoothly into the leading end portion of a radially inner surface of the knife blade and cooperates therewith to define the entirety of the impeller blade surface.
Still another specific object of the invention is to provide a cutterhead, as defined in the immediately preceding object, wherein the removable rail forms an intermediate portion of the impeller surface.
Another object of the invention is to provide a cutterhead provided with knife holders which each include a removable rail that includes an appendage that extends to the mounting surface for the knife holder and defines an surface which cooperates with a radially outer surface of the holder to define a smooth curved impeller surface extending between a underside location of the knife blade trailing the knife cutting edge and the mounting surface for the knife holder.
A further object of the invention is to provide a cutterhead having knife holders which each include a removable insert having a surface which cooperates with another surface of the knife holder to define a smooth impeller surface extending between a mounting surface for the knife holder and a radially inner surface of the cutting knife adjacent a cutting edge of the knife.
These and other objects will become apparent from a reading of the ensuing description together with the appended drawings.